Currently, most of fine patterns for electronic circuits in semiconductor devices, displays, or electronic products are produced by photolithography, but there is a limit to produce inexpensive products with photolithography. In production of electronic products aiming to give a large area, it is difficult to reduce a production cost with a production method using lithography.
Considering the aforementioned trends, so-called “printed electronics,” which produces electronic circuits, sensors, or elements utilizing printing techniques, has been studied. This method has attracted attentions as a production method, which can reduce a usage amount of chemical substances, and is friendly to the environment. Moreover, part of this method has already applied for electrode printing of a membrane keyboard, automobile windshield defogger, or RFID (Radio Frequency Identification) tag antenna.
In the printed electronics, it is important to control wettability of a base (a side where printing is performed on). The control of wettability can be achieved by controlling surface free energy, and various methods have been proposed. Among them, proposed is a base, which is patterned with a difference in surface free energy.
In the technology disclosed in PTL 1, for example, a surface is modified with radial rays applied through a mask, or generated ozone to thereby form a pattern with surface free energy difference. In the technology disclosed in PTL 2, moreover, a low surface free energy area is locally formed by exposure using a difference in light transmittance of Fresnel lens, and then a high surface free energy area is formed by exposing the unexposed area with light in water.
The base of PTL 1 has surface free energy difference formed thereon, but the surface free energy difference is small. In the case where an ink is applied onto the surface of the base, therefore, the ink cannot completely achieve color coding, and the ink merely forms difference in a thickness of the coated film.
The base of PTL 2 similarly has surface free energy difference formed thereon, but color coding cannot be achieved only by applying an ink onto the surface of the base. It is necessary to provide a step for removing the ink from the area where it is not desirable to deposit the ink (a low surface free energy area).